The transition of gramicidin from non-channel to channel form is being investigated using mixed chain phosphatidylcholine lipid bilayers. Heat treatment shifted the fluorescence emission wavelength to shorter wavelengths, as well as, increased the fluorescence anisotropy of the non channel form with little effect to the channel conformer. The rate of transition from non-channel to a channel conformation was found to depend on the bilayer composition. Using fluorescence anisotropy to probe lipid mobility, we found a marked difference in the mobility of lipid acyl chains with channel type. The results of our study may serve as a useful model for similar conformational transitions in other more complex membrane proteins. In a continuation of our work, we extended the above investigation to include the effect of ethanol on the local organization of these lipid bilayer systems.